The subject of the present invention is a lever fastening device according to the preamble to the main claim.
Fastening devices or, in short, "fastenings", of this type are used widely in the field of sports equipment and footwear such as ski boots, snow-board shoes and bindings, and skating boots, for adjustably tightening onto one another two portions of the footwear (or equipment), such as two flaps of the upper.
These fastenings are used mainly for fastening plastics shells or cuffs of boots where, owing to the presence of levers, these fastenings can overcome the resistance offered to the closure of the flaps of the upper by the fairly stiff nature of the material used.
However, the use of conventional lever fastenings involves problems of two kinds which the invention proposes to overcome.
In the first place, the operation of the levers still requires considerable effort during both the opening and the closure of the fastening; this effort is not always in proportion to the user's muscles, particularly in the case of women and children.
In the second place, these levers can be manoeuvred only between a fully-open position and a fully-closed position. In the fully-open position, they project from the shell of the footwear like flags, hampering the user's movements; in the fully-closed position they lock the user's foot down hard so as to produce conditions which are not always comfortable, particularly when the user is not performing any sporting activity but, more simply is taking a rest or a break.
The problem upon which the present invention is based is that of the provision of a fastening device which is designed structurally and functionally so as to overcome all of the problems complained of with reference to the prior art mentioned.